I've just tried this magic wormhole to exchange a file between 2 computers and it worked as a charm without any problems, pretty neat :3
https://github.com/warner/magic-wormhole
But it's quite nerdy: you need to install a command line tool using pip on a linux distribution, but if you are this kind of people it's really cool.
@floi @bram A good friend of mine wrote this tool called servefile for transferring files more easily, mostly on a local network: https://www.unix.com/man-page/debian/1/servefile/
It's nice because you can just give people a link and have them download the file using their browser, which is a familiar thing.
But also, this xkcd comic applies: https://xkcd.com/949/
@NerdResa @floi @bram yea, that xkcd is sooo on point. For LAN, I've been using python -m SimpleHTTPServer. Only really works for single/few files, though, and still requires opening a port on my machine...